Minnesota reported another 434 lab-confirmed cases and three deaths from COVID-19 on Monday, but any spread of the infectious disease caused by holiday weekend gatherings and celebrations won't be detected for a couple of weeks.

The latest counts from the Minnesota Department of Health bring the state to a total of 38,569 cases of COVID-19 confirmed through diagnostic testing and 1,474 deaths.

The state is one of only 14 in the U.S. with flat or declining case growth levels over the past two weeks, according to the COVID Exit Strategy website. As in states with growing case volumes, Minnesota has seen a trend of more COVID-19 detected in younger people.

The number of cases detected in Minnesotans aged 5 to 19 has nearly doubled from 1,752 on June 1 to 3,488 on Monday, while the number of cases among Minnesotans in their 20s has increased nearly 80% from 4,660 to 8,474 in the same time frame.

Severe COVID-19 cases are less common in this age group. Of all COVID-19 deaths in Minnesota, only two involved people 29 or younger. People 70 and older have suffered more than 80% of the deaths, even though they represent only 11% of the state's cases. The number of COVID-19 deaths involving residents of long-term care or assisted-living facilities was 1,156 as of Monday.

The number of people hospitalized for COVID-19 on Monday was 258 — including 125 people needing intensive care — which represents the lowest total since April 22.

State health officials remain concerned about an uptick related to Minnesotans traveling and gathering with family and friends for Independence Day celebrations. Such gatherings could allow infected young people, for example, to spread the novel coronavirus that causes COVID-19 to older people at greater risk of complications or death.

Statewide highway traffic was only .4% below typical levels on July 1, according to the latest data from the Minnesota Department of Transportation, reflecting a continued return to normalcy following the end of a statewide stay-at-home order on May 18, and the gradual, limited reopenings of businesses, restaurants and entertainment venues in June.

Highway traffic had been 65% below normal on April 12, when COVID-19 case growth was accelerating in Minnesota.

Health officials previously said it takes up to 21 days to detect any shift in the pandemic caused by changes in social conditions or restrictions.

No substantial case growth occurred following the mass protests over the May 25 police killing of George Floyd, bolstering theories that the virus isn't as transmissible outdoors. The recent uptick in cases among young adults followed the June 18 limited reopening of bars and restaurants, and subsequent state health reports of outbreaks in bars in Minneapolis and Mankato where patrons weren't following social distancing recommendations or wearing masks.

Many people don't seek testing for COVID-19 due to infections causing mild or no symptoms, and federal health officials late last month estimated that every one detected case probably represents 10 undetected ones.

Among known cases in Minnesota, 33,907 people have recovered to the point that they are no longer considered infection risks or required to isolate themselves.